This report describes a new project in which the biological role of gamma-hydroxybutyrate (GHB) is being investigated. GHB is an endogenous compound which was first found to be present in brain in concentrations ranging from 1 - 4 micromole, but which was later found to be widely distributed throughout the other organs of the body. Pharmacological doses of this hydroxyacid produce catatonic behavior in rats and dose-dependent reductions in the rate of glucose utilization in brain. These effects, and others reported in most of the previous studies, have been elicited by doses of GHB that would produce tissue concentrations of the compound many hundreds of times higher than that which normally exists in brain. Initial studies in this laboratory have shown that concentrations of GHB as low as 1 micromole can alter calcium metabolism in astrocytes cultured from 16 day rat fetuses. The mechanism by which calcium metabolism is altered in these cells is the first objective in this project.